MBMS (Multimedia Broadcast Multicast Service) is used to provide a multimedia broadcast service and a multimedia multicast service for user equipment (UE) in a cell. The multimedia broadcast service may broadcast multimedia video information to all UEs. The multimedia multicast service may send some paid multimedia video information to a group of subscribed UEs for watching.
In an LTE (Long Term Evolution) system, when an MBMS mode is used to transmit a physical multicast channel (PMCH), a network side device transmits, on an MBMS point-to-multipoint control channel (MCCH), a modulation and coding scheme (MCS) index for an MBMS point-to-multipoint traffic channel (MTCH). Different MCS indexes correspond to different MCS configuration information. The configuration information includes a modulation scheme used when a transmitted MTCH is modulated and encoded, such as quadrature phase shift keying (QPSK) modulation, 16 quadrature amplitude modulation (QAM), or 64 QAM. AUE demodulates the received MTCH according to the configuration information.
Because of relatively poor environment quality (a relatively low signal-to-noise ratio) of a channel between cell-edge UE and a base station, to ensure service transmission robustness, when service data is transmitted to the cell-edge UE, a low-order modulation and coding scheme such as QPSK needs to be used. Because of relatively good environment quality (a relatively high signal-to-noise ratio) of a channel between cell-center UE and a base station, when service data is transmitted to the cell-center UE, a high-order modulation and coding scheme such as 16 QAM or 64QAM may be used to improve a signal transmission bit rate. In the LTE system, when MBMS data is broadcast to all UEs within the cell, to ensure that both the cell-center UE and the cell-edge UE can receive the MBMS data, only the low-order modulation and coding scheme can be selected. In this way, an overall system throughput is reduced, and system spectrum utilization efficiency is relatively low.